gccgo.go

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package work
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"os"
    11  	"os/exec"
    12  	"path/filepath"
    13  	"strings"
    14  	"sync"
    15  
    16  	"cmd/go/internal/base"
    17  	"cmd/go/internal/cfg"
    18  	"cmd/go/internal/fsys"
    19  	"cmd/go/internal/load"
    20  	"cmd/go/internal/str"
    21  	"cmd/internal/pathcache"
    22  	"cmd/internal/pkgpath"
    23  )
    24  
    25  // The Gccgo toolchain.
    26  
    27  type gccgoToolchain struct{}
    28  
    29  var GccgoName, GccgoBin string
    30  var GccgoChanged bool
    31  var gccgoErr error
    32  
    33  func init() {
    34  	GccgoName = cfg.Getenv("GCCGO")
    35  	if GccgoName == "" {
    36  		GccgoName = "gccgo"
    37  	}
    38  	if GccgoName != "gccgo" {
    39  		GccgoChanged = true
    40  	}
    41  	GccgoBin, gccgoErr = pathcache.LookPath(GccgoName)
    42  }
    43  
    44  func (gccgoToolchain) compiler() string {
    45  	checkGccgoBin()
    46  	return GccgoBin
    47  }
    48  
    49  func (gccgoToolchain) linker() string {
    50  	checkGccgoBin()
    51  	return GccgoBin
    52  }
    53  
    54  func (gccgoToolchain) ar() []string {
    55  	return envList("AR", "ar")
    56  }
    57  
    58  func checkGccgoBin() {
    59  	if gccgoErr == nil {
    60  		return
    61  	}
    62  	fmt.Fprintf(os.Stderr, "cmd/go: gccgo: %s\n", gccgoErr)
    63  	base.SetExitStatus(2)
    64  	base.Exit()
    65  }
    66  
    67  func (tools gccgoToolchain) gc(b *Builder, a *Action, archive string, importcfg, embedcfg []byte, symabis string, asmhdr bool, pgoProfile string, gofiles []string) (ofile string, output []byte, err error) {
    68  	p := a.Package
    69  	sh := b.Shell(a)
    70  	objdir := a.Objdir
    71  	out := "_go_.o"
    72  	ofile = objdir + out
    73  	gcargs := []string{"-g"}
    74  	gcargs = append(gcargs, b.gccArchArgs()...)
    75  	gcargs = append(gcargs, "-fdebug-prefix-map="+b.WorkDir+"=/tmp/go-build")
    76  	gcargs = append(gcargs, "-gno-record-gcc-switches")
    77  	if pkgpath := gccgoPkgpath(p); pkgpath != "" {
    78  		gcargs = append(gcargs, "-fgo-pkgpath="+pkgpath)
    79  	}
    80  	if p.Internal.LocalPrefix != "" {
    81  		gcargs = append(gcargs, "-fgo-relative-import-path="+p.Internal.LocalPrefix)
    82  	}
    83  
    84  	args := str.StringList(tools.compiler(), "-c", gcargs, "-o", ofile, forcedGccgoflags)
    85  	if importcfg != nil {
    86  		if b.gccSupportsFlag(args[:1], "-fgo-importcfg=/dev/null") {
    87  			if err := sh.writeFile(objdir+"importcfg", importcfg); err != nil {
    88  				return "", nil, err
    89  			}
    90  			args = append(args, "-fgo-importcfg="+objdir+"importcfg")
    91  		} else {
    92  			root := objdir + "_importcfgroot_"
    93  			if err := buildImportcfgSymlinks(sh, root, importcfg); err != nil {
    94  				return "", nil, err
    95  			}
    96  			args = append(args, "-I", root)
    97  		}
    98  	}
    99  	if embedcfg != nil && b.gccSupportsFlag(args[:1], "-fgo-embedcfg=/dev/null") {
   100  		if err := sh.writeFile(objdir+"embedcfg", embedcfg); err != nil {
   101  			return "", nil, err
   102  		}
   103  		args = append(args, "-fgo-embedcfg="+objdir+"embedcfg")
   104  	}
   105  
   106  	if b.gccSupportsFlag(args[:1], "-ffile-prefix-map=a=b") {
   107  		if cfg.BuildTrimpath {
   108  			args = append(args, "-ffile-prefix-map="+base.Cwd()+"=.")
   109  			args = append(args, "-ffile-prefix-map="+b.WorkDir+"=/tmp/go-build")
   110  		}
   111  		if fsys.OverlayFile != "" {
   112  			for _, name := range gofiles {
   113  				absPath := mkAbs(p.Dir, name)
   114  				if !fsys.Replaced(absPath) {
   115  					continue
   116  				}
   117  				toPath := absPath
   118  				// gccgo only applies the last matching rule, so also handle the case where
   119  				// BuildTrimpath is true and the path is relative to base.Cwd().
   120  				if cfg.BuildTrimpath && str.HasFilePathPrefix(toPath, base.Cwd()) {
   121  					toPath = "." + toPath[len(base.Cwd()):]
   122  				}
   123  				args = append(args, "-ffile-prefix-map="+fsys.Actual(absPath)+"="+toPath)
   124  			}
   125  		}
   126  	}
   127  
   128  	args = append(args, a.Package.Internal.Gccgoflags...)
   129  	for _, f := range gofiles {
   130  		f := mkAbs(p.Dir, f)
   131  		// Overlay files if necessary.
   132  		// See comment on gctoolchain.gc about overlay TODOs
   133  		args = append(args, fsys.Actual(f))
   134  	}
   135  
   136  	output, err = sh.runOut(p.Dir, nil, args)
   137  	return ofile, output, err
   138  }
   139  
   140  // buildImportcfgSymlinks builds in root a tree of symlinks
   141  // implementing the directives from importcfg.
   142  // This serves as a temporary transition mechanism until
   143  // we can depend on gccgo reading an importcfg directly.
   144  // (The Go 1.9 and later gc compilers already do.)
   145  func buildImportcfgSymlinks(sh *Shell, root string, importcfg []byte) error {
   146  	for lineNum, line := range strings.Split(string(importcfg), "\n") {
   147  		lineNum++ // 1-based
   148  		line = strings.TrimSpace(line)
   149  		if line == "" {
   150  			continue
   151  		}
   152  		if line == "" || strings.HasPrefix(line, "#") {
   153  			continue
   154  		}
   155  		var verb, args string
   156  		if i := strings.Index(line, " "); i < 0 {
   157  			verb = line
   158  		} else {
   159  			verb, args = line[:i], strings.TrimSpace(line[i+1:])
   160  		}
   161  		before, after, _ := strings.Cut(args, "=")
   162  		switch verb {
   163  		default:
   164  			base.Fatalf("importcfg:%d: unknown directive %q", lineNum, verb)
   165  		case "packagefile":
   166  			if before == "" || after == "" {
   167  				return fmt.Errorf(`importcfg:%d: invalid packagefile: syntax is "packagefile path=filename": %s`, lineNum, line)
   168  			}
   169  			archive := gccgoArchive(root, before)
   170  			if err := sh.Mkdir(filepath.Dir(archive)); err != nil {
   171  				return err
   172  			}
   173  			if err := sh.Symlink(after, archive); err != nil {
   174  				return err
   175  			}
   176  		case "importmap":
   177  			if before == "" || after == "" {
   178  				return fmt.Errorf(`importcfg:%d: invalid importmap: syntax is "importmap old=new": %s`, lineNum, line)
   179  			}
   180  			beforeA := gccgoArchive(root, before)
   181  			afterA := gccgoArchive(root, after)
   182  			if err := sh.Mkdir(filepath.Dir(beforeA)); err != nil {
   183  				return err
   184  			}
   185  			if err := sh.Mkdir(filepath.Dir(afterA)); err != nil {
   186  				return err
   187  			}
   188  			if err := sh.Symlink(afterA, beforeA); err != nil {
   189  				return err
   190  			}
   191  		case "packageshlib":
   192  			return fmt.Errorf("gccgo -importcfg does not support shared libraries")
   193  		}
   194  	}
   195  	return nil
   196  }
   197  
   198  func (tools gccgoToolchain) asm(b *Builder, a *Action, sfiles []string) ([]string, error) {
   199  	p := a.Package
   200  	var ofiles []string
   201  	for _, sfile := range sfiles {
   202  		base := filepath.Base(sfile)
   203  		ofile := a.Objdir + base[:len(base)-len(".s")] + ".o"
   204  		ofiles = append(ofiles, ofile)
   205  		sfile = fsys.Actual(mkAbs(p.Dir, sfile))
   206  		defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
   207  		if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
   208  			defs = append(defs, `-D`, `GOPKGPATH=`+pkgpath)
   209  		}
   210  		defs = tools.maybePIC(defs)
   211  		defs = append(defs, b.gccArchArgs()...)
   212  		err := b.Shell(a).run(p.Dir, p.ImportPath, nil, tools.compiler(), "-xassembler-with-cpp", "-I", a.Objdir, "-c", "-o", ofile, defs, sfile)
   213  		if err != nil {
   214  			return nil, err
   215  		}
   216  	}
   217  	return ofiles, nil
   218  }
   219  
   220  func (gccgoToolchain) symabis(b *Builder, a *Action, sfiles []string) (string, error) {
   221  	return "", nil
   222  }
   223  
   224  func gccgoArchive(basedir, imp string) string {
   225  	end := filepath.FromSlash(imp + ".a")
   226  	afile := filepath.Join(basedir, end)
   227  	// add "lib" to the final element
   228  	return filepath.Join(filepath.Dir(afile), "lib"+filepath.Base(afile))
   229  }
   230  
   231  func (tools gccgoToolchain) pack(b *Builder, a *Action, afile string, ofiles []string) error {
   232  	p := a.Package
   233  	sh := b.Shell(a)
   234  	objdir := a.Objdir
   235  	absOfiles := make([]string, 0, len(ofiles))
   236  	for _, f := range ofiles {
   237  		absOfiles = append(absOfiles, mkAbs(objdir, f))
   238  	}
   239  	var arArgs []string
   240  	if cfg.Goos == "aix" && cfg.Goarch == "ppc64" {
   241  		// AIX puts both 32-bit and 64-bit objects in the same archive.
   242  		// Tell the AIX "ar" command to only care about 64-bit objects.
   243  		arArgs = []string{"-X64"}
   244  	}
   245  	absAfile := mkAbs(objdir, afile)
   246  	// Try with D modifier first, then without if that fails.
   247  	output, err := sh.runOut(p.Dir, nil, tools.ar(), arArgs, "rcD", absAfile, absOfiles)
   248  	if err != nil {
   249  		return sh.run(p.Dir, p.ImportPath, nil, tools.ar(), arArgs, "rc", absAfile, absOfiles)
   250  	}
   251  
   252  	// Show the output if there is any even without errors.
   253  	return sh.reportCmd("", "", output, nil)
   254  }
   255  
   256  func (tools gccgoToolchain) link(b *Builder, root *Action, out, importcfg string, allactions []*Action, buildmode, desc string) error {
   257  	sh := b.Shell(root)
   258  
   259  	// gccgo needs explicit linking with all package dependencies,
   260  	// and all LDFLAGS from cgo dependencies.
   261  	afiles := []string{}
   262  	shlibs := []string{}
   263  	ldflags := b.gccArchArgs()
   264  	cgoldflags := []string{}
   265  	usesCgo := false
   266  	cxx := false
   267  	objc := false
   268  	fortran := false
   269  	if root.Package != nil {
   270  		cxx = len(root.Package.CXXFiles) > 0 || len(root.Package.SwigCXXFiles) > 0
   271  		objc = len(root.Package.MFiles) > 0
   272  		fortran = len(root.Package.FFiles) > 0
   273  	}
   274  
   275  	readCgoFlags := func(flagsFile string) error {
   276  		flags, err := os.ReadFile(flagsFile)
   277  		if err != nil {
   278  			return err
   279  		}
   280  		const ldflagsPrefix = "_CGO_LDFLAGS="
   281  		for _, line := range strings.Split(string(flags), "\n") {
   282  			if strings.HasPrefix(line, ldflagsPrefix) {
   283  				flag := line[len(ldflagsPrefix):]
   284  				// Every _cgo_flags file has -g and -O2 in _CGO_LDFLAGS
   285  				// but they don't mean anything to the linker so filter
   286  				// them out.
   287  				if flag != "-g" && !strings.HasPrefix(flag, "-O") {
   288  					cgoldflags = append(cgoldflags, flag)
   289  				}
   290  			}
   291  		}
   292  		return nil
   293  	}
   294  
   295  	var arArgs []string
   296  	if cfg.Goos == "aix" && cfg.Goarch == "ppc64" {
   297  		// AIX puts both 32-bit and 64-bit objects in the same archive.
   298  		// Tell the AIX "ar" command to only care about 64-bit objects.
   299  		arArgs = []string{"-X64"}
   300  	}
   301  
   302  	newID := 0
   303  	readAndRemoveCgoFlags := func(archive string) (string, error) {
   304  		newID++
   305  		newArchive := root.Objdir + fmt.Sprintf("_pkg%d_.a", newID)
   306  		if err := sh.CopyFile(newArchive, archive, 0666, false); err != nil {
   307  			return "", err
   308  		}
   309  		if cfg.BuildN || cfg.BuildX {
   310  			sh.ShowCmd("", "ar d %s _cgo_flags", newArchive)
   311  			if cfg.BuildN {
   312  				// TODO(rsc): We could do better about showing the right _cgo_flags even in -n mode.
   313  				// Either the archive is already built and we can read them out,
   314  				// or we're printing commands to build the archive and can
   315  				// forward the _cgo_flags directly to this step.
   316  				return "", nil
   317  			}
   318  		}
   319  		err := sh.run(root.Objdir, desc, nil, tools.ar(), arArgs, "x", newArchive, "_cgo_flags")
   320  		if err != nil {
   321  			return "", err
   322  		}
   323  		err = sh.run(".", desc, nil, tools.ar(), arArgs, "d", newArchive, "_cgo_flags")
   324  		if err != nil {
   325  			return "", err
   326  		}
   327  		err = readCgoFlags(filepath.Join(root.Objdir, "_cgo_flags"))
   328  		if err != nil {
   329  			return "", err
   330  		}
   331  		return newArchive, nil
   332  	}
   333  
   334  	// If using -linkshared, find the shared library deps.
   335  	haveShlib := make(map[string]bool)
   336  	targetBase := filepath.Base(root.Target)
   337  	if cfg.BuildLinkshared {
   338  		for _, a := range root.Deps {
   339  			p := a.Package
   340  			if p == nil || p.Shlib == "" {
   341  				continue
   342  			}
   343  
   344  			// The .a we are linking into this .so
   345  			// will have its Shlib set to this .so.
   346  			// Don't start thinking we want to link
   347  			// this .so into itself.
   348  			base := filepath.Base(p.Shlib)
   349  			if base != targetBase {
   350  				haveShlib[base] = true
   351  			}
   352  		}
   353  	}
   354  
   355  	// Arrange the deps into afiles and shlibs.
   356  	addedShlib := make(map[string]bool)
   357  	for _, a := range root.Deps {
   358  		p := a.Package
   359  		if p != nil && p.Shlib != "" && haveShlib[filepath.Base(p.Shlib)] {
   360  			// This is a package linked into a shared
   361  			// library that we will put into shlibs.
   362  			continue
   363  		}
   364  
   365  		if haveShlib[filepath.Base(a.Target)] {
   366  			// This is a shared library we want to link against.
   367  			if !addedShlib[a.Target] {
   368  				shlibs = append(shlibs, a.Target)
   369  				addedShlib[a.Target] = true
   370  			}
   371  			continue
   372  		}
   373  
   374  		if p != nil {
   375  			target := a.built
   376  			if p.UsesCgo() || p.UsesSwig() {
   377  				var err error
   378  				target, err = readAndRemoveCgoFlags(target)
   379  				if err != nil {
   380  					continue
   381  				}
   382  			}
   383  
   384  			afiles = append(afiles, target)
   385  		}
   386  	}
   387  
   388  	for _, a := range allactions {
   389  		if a.Package == nil {
   390  			continue
   391  		}
   392  		if len(a.Package.CgoFiles) > 0 {
   393  			usesCgo = true
   394  		}
   395  		if a.Package.UsesSwig() {
   396  			usesCgo = true
   397  		}
   398  		if len(a.Package.CXXFiles) > 0 || len(a.Package.SwigCXXFiles) > 0 {
   399  			cxx = true
   400  		}
   401  		if len(a.Package.MFiles) > 0 {
   402  			objc = true
   403  		}
   404  		if len(a.Package.FFiles) > 0 {
   405  			fortran = true
   406  		}
   407  	}
   408  
   409  	wholeArchive := []string{"-Wl,--whole-archive"}
   410  	noWholeArchive := []string{"-Wl,--no-whole-archive"}
   411  	if cfg.Goos == "aix" {
   412  		wholeArchive = nil
   413  		noWholeArchive = nil
   414  	}
   415  	ldflags = append(ldflags, wholeArchive...)
   416  	ldflags = append(ldflags, afiles...)
   417  	ldflags = append(ldflags, noWholeArchive...)
   418  
   419  	ldflags = append(ldflags, cgoldflags...)
   420  	ldflags = append(ldflags, envList("CGO_LDFLAGS", "")...)
   421  	if cfg.Goos != "aix" {
   422  		ldflags = str.StringList("-Wl,-(", ldflags, "-Wl,-)")
   423  	}
   424  
   425  	if root.buildID != "" {
   426  		// On systems that normally use gold or the GNU linker,
   427  		// use the --build-id option to write a GNU build ID note.
   428  		switch cfg.Goos {
   429  		case "android", "dragonfly", "linux", "netbsd":
   430  			ldflags = append(ldflags, fmt.Sprintf("-Wl,--build-id=0x%x", root.buildID))
   431  		}
   432  	}
   433  
   434  	var rLibPath string
   435  	if cfg.Goos == "aix" {
   436  		rLibPath = "-Wl,-blibpath="
   437  	} else {
   438  		rLibPath = "-Wl,-rpath="
   439  	}
   440  	for _, shlib := range shlibs {
   441  		ldflags = append(
   442  			ldflags,
   443  			"-L"+filepath.Dir(shlib),
   444  			rLibPath+filepath.Dir(shlib),
   445  			"-l"+strings.TrimSuffix(
   446  				strings.TrimPrefix(filepath.Base(shlib), "lib"),
   447  				".so"))
   448  	}
   449  
   450  	var realOut string
   451  	goLibBegin := str.StringList(wholeArchive, "-lgolibbegin", noWholeArchive)
   452  	switch buildmode {
   453  	case "exe":
   454  		if usesCgo && cfg.Goos == "linux" {
   455  			ldflags = append(ldflags, "-Wl,-E")
   456  		}
   457  
   458  	case "c-archive":
   459  		// Link the Go files into a single .o, and also link
   460  		// in -lgolibbegin.
   461  		//
   462  		// We need to use --whole-archive with -lgolibbegin
   463  		// because it doesn't define any symbols that will
   464  		// cause the contents to be pulled in; it's just
   465  		// initialization code.
   466  		//
   467  		// The user remains responsible for linking against
   468  		// -lgo -lpthread -lm in the final link. We can't use
   469  		// -r to pick them up because we can't combine
   470  		// split-stack and non-split-stack code in a single -r
   471  		// link, and libgo picks up non-split-stack code from
   472  		// libffi.
   473  		ldflags = append(ldflags, "-Wl,-r", "-nostdlib")
   474  		ldflags = append(ldflags, goLibBegin...)
   475  
   476  		if nopie := b.gccNoPie([]string{tools.linker()}); nopie != "" {
   477  			ldflags = append(ldflags, nopie)
   478  		}
   479  
   480  		// We are creating an object file, so we don't want a build ID.
   481  		if root.buildID == "" {
   482  			ldflags = b.disableBuildID(ldflags)
   483  		}
   484  
   485  		realOut = out
   486  		out = out + ".o"
   487  
   488  	case "c-shared":
   489  		ldflags = append(ldflags, "-shared", "-nostdlib")
   490  		if cfg.Goos != "windows" {
   491  			ldflags = append(ldflags, "-Wl,-z,nodelete")
   492  		}
   493  		ldflags = append(ldflags, goLibBegin...)
   494  		ldflags = append(ldflags, "-lgo", "-lgcc_s", "-lgcc", "-lc", "-lgcc")
   495  
   496  	case "shared":
   497  		if cfg.Goos != "aix" {
   498  			ldflags = append(ldflags, "-zdefs")
   499  		}
   500  		ldflags = append(ldflags, "-shared", "-nostdlib", "-lgo", "-lgcc_s", "-lgcc", "-lc")
   501  
   502  	default:
   503  		base.Fatalf("-buildmode=%s not supported for gccgo", buildmode)
   504  	}
   505  
   506  	switch buildmode {
   507  	case "exe", "c-shared":
   508  		if cxx {
   509  			ldflags = append(ldflags, "-lstdc++")
   510  		}
   511  		if objc {
   512  			ldflags = append(ldflags, "-lobjc")
   513  		}
   514  		if fortran {
   515  			fc := cfg.Getenv("FC")
   516  			if fc == "" {
   517  				fc = "gfortran"
   518  			}
   519  			// support gfortran out of the box and let others pass the correct link options
   520  			// via CGO_LDFLAGS
   521  			if strings.Contains(fc, "gfortran") {
   522  				ldflags = append(ldflags, "-lgfortran")
   523  			}
   524  		}
   525  	}
   526  
   527  	if err := sh.run(".", desc, nil, tools.linker(), "-o", out, ldflags, forcedGccgoflags, root.Package.Internal.Gccgoflags); err != nil {
   528  		return err
   529  	}
   530  
   531  	switch buildmode {
   532  	case "c-archive":
   533  		if err := sh.run(".", desc, nil, tools.ar(), arArgs, "rc", realOut, out); err != nil {
   534  			return err
   535  		}
   536  	}
   537  	return nil
   538  }
   539  
   540  func (tools gccgoToolchain) ld(b *Builder, root *Action, targetPath, importcfg, mainpkg string) error {
   541  	return tools.link(b, root, targetPath, importcfg, root.Deps, ldBuildmode, root.Package.ImportPath)
   542  }
   543  
   544  func (tools gccgoToolchain) ldShared(b *Builder, root *Action, toplevelactions []*Action, targetPath, importcfg string, allactions []*Action) error {
   545  	return tools.link(b, root, targetPath, importcfg, allactions, "shared", targetPath)
   546  }
   547  
   548  func (tools gccgoToolchain) cc(b *Builder, a *Action, ofile, cfile string) error {
   549  	p := a.Package
   550  	inc := filepath.Join(cfg.GOROOT, "pkg", "include")
   551  	cfile = mkAbs(p.Dir, cfile)
   552  	defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
   553  	defs = append(defs, b.gccArchArgs()...)
   554  	if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
   555  		defs = append(defs, `-D`, `GOPKGPATH="`+pkgpath+`"`)
   556  	}
   557  	compiler := envList("CC", cfg.DefaultCC(cfg.Goos, cfg.Goarch))
   558  	if b.gccSupportsFlag(compiler, "-fsplit-stack") {
   559  		defs = append(defs, "-fsplit-stack")
   560  	}
   561  	defs = tools.maybePIC(defs)
   562  	if b.gccSupportsFlag(compiler, "-ffile-prefix-map=a=b") {
   563  		defs = append(defs, "-ffile-prefix-map="+base.Cwd()+"=.")
   564  		defs = append(defs, "-ffile-prefix-map="+b.WorkDir+"=/tmp/go-build")
   565  	} else if b.gccSupportsFlag(compiler, "-fdebug-prefix-map=a=b") {
   566  		defs = append(defs, "-fdebug-prefix-map="+b.WorkDir+"=/tmp/go-build")
   567  	}
   568  	if b.gccSupportsFlag(compiler, "-gno-record-gcc-switches") {
   569  		defs = append(defs, "-gno-record-gcc-switches")
   570  	}
   571  	return b.Shell(a).run(p.Dir, p.ImportPath, nil, compiler, "-Wall", "-g",
   572  		"-I", a.Objdir, "-I", inc, "-o", ofile, defs, "-c", cfile)
   573  }
   574  
   575  // maybePIC adds -fPIC to the list of arguments if needed.
   576  func (tools gccgoToolchain) maybePIC(args []string) []string {
   577  	switch cfg.BuildBuildmode {
   578  	case "c-shared", "shared", "plugin":
   579  		args = append(args, "-fPIC")
   580  	}
   581  	return args
   582  }
   583  
   584  func gccgoPkgpath(p *load.Package) string {
   585  	if p.Internal.Build.IsCommand() && !p.Internal.ForceLibrary {
   586  		return ""
   587  	}
   588  	return p.ImportPath
   589  }
   590  
   591  var gccgoToSymbolFuncOnce sync.Once
   592  var gccgoToSymbolFunc func(string) string
   593  
   594  func (tools gccgoToolchain) gccgoCleanPkgpath(b *Builder, p *load.Package) string {
   595  	gccgoToSymbolFuncOnce.Do(func() {
   596  		tmpdir := b.WorkDir
   597  		if cfg.BuildN {
   598  			tmpdir = os.TempDir()
   599  		}
   600  		fn, err := pkgpath.ToSymbolFunc(tools.compiler(), tmpdir)
   601  		if err != nil {
   602  			fmt.Fprintf(os.Stderr, "cmd/go: %v\n", err)
   603  			base.SetExitStatus(2)
   604  			base.Exit()
   605  		}
   606  		gccgoToSymbolFunc = fn
   607  	})
   608  
   609  	return gccgoToSymbolFunc(gccgoPkgpath(p))
   610  }
   611  
   612  var (
   613  	gccgoSupportsCgoIncompleteOnce sync.Once
   614  	gccgoSupportsCgoIncomplete     bool
   615  )
   616  
   617  const gccgoSupportsCgoIncompleteCode = `
   618  package p
   619  
   620  import "runtime/cgo"
   621  
   622  type I cgo.Incomplete
   623  `
   624  
   625  // supportsCgoIncomplete reports whether the gccgo/GoLLVM compiler
   626  // being used supports cgo.Incomplete, which was added in GCC 13.
   627  //
   628  // This takes an Action only for output reporting purposes.
   629  // The result value is unrelated to the Action.
   630  func (tools gccgoToolchain) supportsCgoIncomplete(b *Builder, a *Action) bool {
   631  	gccgoSupportsCgoIncompleteOnce.Do(func() {
   632  		sh := b.Shell(a)
   633  
   634  		fail := func(err error) {
   635  			fmt.Fprintf(os.Stderr, "cmd/go: %v\n", err)
   636  			base.SetExitStatus(2)
   637  			base.Exit()
   638  		}
   639  
   640  		tmpdir := b.WorkDir
   641  		if cfg.BuildN {
   642  			tmpdir = os.TempDir()
   643  		}
   644  		f, err := os.CreateTemp(tmpdir, "*_gccgo_cgoincomplete.go")
   645  		if err != nil {
   646  			fail(err)
   647  		}
   648  		fn := f.Name()
   649  		f.Close()
   650  		defer os.Remove(fn)
   651  
   652  		if err := os.WriteFile(fn, []byte(gccgoSupportsCgoIncompleteCode), 0644); err != nil {
   653  			fail(err)
   654  		}
   655  
   656  		on := strings.TrimSuffix(fn, ".go") + ".o"
   657  		if cfg.BuildN || cfg.BuildX {
   658  			sh.ShowCmd(tmpdir, "%s -c -o %s %s || true", tools.compiler(), on, fn)
   659  			// Since this function affects later builds,
   660  			// and only generates temporary files,
   661  			// we run the command even with -n.
   662  		}
   663  		cmd := exec.Command(tools.compiler(), "-c", "-o", on, fn)
   664  		cmd.Dir = tmpdir
   665  		var buf bytes.Buffer
   666  		cmd.Stdout = &buf
   667  		cmd.Stderr = &buf
   668  		err = cmd.Run()
   669  		gccgoSupportsCgoIncomplete = err == nil
   670  		if cfg.BuildN || cfg.BuildX {
   671  			// Show output. We always pass a nil err because errors are an
   672  			// expected outcome in this case.
   673  			desc := sh.fmtCmd(tmpdir, "%s -c -o %s %s", tools.compiler(), on, fn)
   674  			sh.reportCmd(desc, tmpdir, buf.Bytes(), nil)
   675  		}
   676  	})
   677  	return gccgoSupportsCgoIncomplete
   678  }
   679
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